SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ae9ae8353cff0f4850caec1e93f8ff11741a09421f703699c908635966c9728' 
  AND token = 'N+girp3cu+AhJjnqGTs5FZlDHqLHNFJcJzzqKZjK920=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}